In order to evaluate the theoretical expressions (Eq. (REF ) or Eq. (REF )) for the slip velocity, we need to compute the concentration distribution \(c_i(z)\)  of all species \(i\)  as a function of the distance \(z\)  from the wall, and the viscosity \(\eta \)  of the solution.
The former is obtained from EMD simulations, and relatively short runs are required as the equilibration in the \(z\) -direction is fast.
In the simplest theoretical description, the viscosity is assumed to be independent of \(z\) , and equal to its bulk value: \(\eta (z) = \eta ^B\) . \(\eta ^B\)  was obtained using the Green-Kubo expression [1]}.
Assuming that \(\eta \)  is independent of \(z\)  is a strong assumption, as we know that the fluid shows layering near the wall.
